After going in at the break a goal behind, the west London side struck five in the second half to book their place in the semi-final of the competition, with a two-legged tie against Swansea to look forward to.

With Juan Mata, Branislav Ivanovic, Victor Moses, Eden Hazard and Fernando Torres all getting on the scoresheet, Chelsea have now scored 17 goals in their last five games across all competition - but Benitez believes there is still plenty of room left for improvement.

"I think we are doing well in attack, still we can still improve," Benitez told reporters.

"We were also talking about the goal that we concede. We know David [Luiz] made a mistake in the pass [for the Leeds goal] but still the team has to react in a different way.

"This is the side of things we want to improve and we don’t have so much time because we don’t have so many training sessions together.

"It was good in Japan because we could practise some things. But still we need time to improve. I’m happy only one goal and not too many chances. We can improve."

With an important home game against an improving Aston Villa side next up for Chelsea on Sunday, Benitez is not getting carried away with the team's clinical display, before revealing that captain John Terry's knee complaint is still causing him problems.

He added: "My priority is to win against Aston Villa [on Sunday], enjoy this [Leeds] game and after it will be a question of time whether we can play at this level and winning games will be easier having everybody together.

"One day he [Terry] is fine, the next day the knee has some trouble. Whether it is a week or three days [before he returns], we don’t yet know."